Anyone who is a regular bed maker will acknowledge the great benefit of contour sheets. However, one disadvantage of contour sheets is that some corners of the mattress are difficult to engage by the corners of the sheet. This is particularly true the closer one gets to the last corner of the mattress, and if one started at the wrong corner and finishes at a hard to get position, it can require a herculean effort to elevate the mattress corner in order to pull the sheet over it.
This problem is particularly aggravated with waterbeds because not only is the corner heavy and awkward but one cannot get one's hand beneath the waterbed because of the typical waterbed frame, making it extremely difficult, especially to accommodate the last corner, at which the sheet is ordinarily rather tight.